.TH std::erase_if(std::multiset) 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::erase_if(std::multiset) \- std::erase_if(std::multiset)

.SH Synopsis
   Defined in header <set>
   template< class Key, class Compare, class Alloc,

             class Pred >
   std::multiset<Key, Compare, Alloc>::size_type         \fI(since C++20)\fP
       erase_if( std::multiset<Key, Compare, Alloc>& c,

                 Pred pred );

   Erases all elements that satisfy the predicate pred from c.

   Equivalent to

 auto old_size = c.size();
 for (auto first = c.begin(), last = c.end(); first != last;)
 {
     if (pred(*first))
         first = c.erase(first);
     else
         ++first;
 }
 return old_size - c.size();

.SH Parameters

   c    - container from which to erase
   pred - predicate that returns true if the element should be erased

.SH Return value

   The number of erased elements.

.SH Complexity

   Linear.

.SH Example


// Run this code

 #include <iostream>
 #include <set>

 void println(auto rem, auto const& container)
 {
     std::cout << rem << '{';
     for (char sep[]{0, ' ', 0}; const auto& item : container)
         std::cout << sep << item, *sep = ',';
     std::cout << "}\\n";
 }

 int main()
 {
     std::multiset data{3, 3, 4, 5, 5, 6, 6, 7, 2, 1, 0};
     println("Original:\\n", data);

     auto divisible_by_3 = [](auto const& x) { return (x % 3) == 0; };

     const auto count = std::erase_if(data, divisible_by_3);

     println("Erase all items divisible by 3:\\n", data);
     std::cout << count << " items erased.\\n";
 }

.SH Output:

 Original:
 {0, 1, 2, 3, 3, 4, 5, 5, 6, 6, 7}
 Erase all items divisible by 3:
 {1, 2, 4, 5, 5, 7}
 5 items erased.

.SH See also

   remove    removes elements satisfying specific criteria
   remove_if \fI(function template)\fP
